Currently known techniques for the treatment and recovery of the materials referred to above are for the most part aimed at:                declassing the degree of hazard of the waste by conditioning it prior to its disposal in a landfill in the case where it is not possible to reach an effective abatement of the contaminants;        rendering sludges inert, dehumidifying/drying or solidifying them.Listed below are some of the most widespread treatment technologies adopted according to the nature of the materials, the contaminated residue, or the waste, which contemplate in part also the use of quicklime.        
A. Urban solid waste (USW)
Urban solid waste (USW), including differentiated and non-differentiated damp waste and non-differentiated waste of vegetable origin and the possible damp fraction of differentiated waste are disposed of as follows:                disposal in landfills, with or without recovery of materials and/or energy;        compaction with or without quicklime;        compaction in waterproof bales;        incineration with or without recovery of energy;        composting of the differentiated damp solid waste and waste of vegetable origin.        
Once disposed of, however, the management of the USW involves a series of disadvantages, amongst which:                the difficulty of selection for a possible further differentiated recovery;        the risk of pollution of groundwater and air;        a negative social and environmental impact.        
B. Sludge
Sludge may be classified into two types: hazardous sludge and non-hazardous sludge.
Non-hazardous sludge, which is generated by urban installations for water treatment, undergoes:                centrifugal separation and disposal in landfills;        thermal drying prior to disposal in landfills or composting;        inertization and dehumidification with quicklime in ground or granulated form;        incineration.        
Hazardous sludge, generated by industrial water-treatment installations, contains metals and non-metabolized compounds, and undergoes:                centrifugal separation and disposal in landfills;        thermal drying prior to disposal in landfills;        inertization and dehumidification with quicklime in ground or granulated form;        fixation with mixes of cement-bentonite mortars prior to disposal in landfills;        incineration        
C. Residue of Industrial Processes
Industrial residue may be solid, semi-solid, pasty and/or damp.
Solid industrial residue waste undergoes:                disposal in classified landfills or recycling.        
Semi-solid, pasty and liquid industrial residue undergoes:                centrifugal separation;        chemical washing and subsequent treatment of the fluid solvent and disposal in landfills or incineration of the resultant solid matter;        inertization with ground or granular slaked lime, which leaves a pasty residue, or with quicklime, which leaves a dry residue: the two techniques are applied for declassing the waste from hazardous to non-hazardous; the waste is in any case disposed of in landfills;        thermal and chemical oxidation;        fixation with mixes of cement-bentonite mortars;        incineration.        
D. Soils
Contaminated soils and inert materials undergo:                disposal in landfills;        chemical or microbiological treatment, which may be conclusive;        inertization with powdered or granular quicklime, which, at the current state of the art, produces only declassing of the waste and not reclamation of the contaminated soil in compliance with regulatory standards;        chemical washing;        incineration.        